Method for producing toner

ABSTRACT

A method for producing a toner including the steps of melt-kneading at least a resin binder and a colorant to give a kneaded product (step 1); and heat-treating the kneaded product obtained in the step 1 (step 2), wherein the resin binder contains a crystalline resin and an amorphous resin, wherein the crystalline resin contains a specified composite resin containing (a) a specified polycondensation resin component and (b) a styrenic resin component, in a specified weight ratio, wherein the composite resin is contained in the resin binder in a specified amount. The toner obtained by the above method is used in, for example, the development of a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method or the like.

FIELD OF THE INVENTION

The present invention relates to a method for producing a toner, whichis used in, for example, the development of a latent image formed inelectrophotography, electrostatic recording method, electrostaticprinting method or the like.

BACKGROUND OF THE INVENTION

For the demands of speeding-up, miniaturization, and the like in therecent years, a toner that is capable of being fixed at an even lowertemperature is in demand. In order to meet such a demand, a toner inwhich a resin binder containing a crystalline resin and an amorphousresin is used is proposed. While a toner in which a crystalline resinand an amorphous resin are used as described above has improvedlow-temperature fixing ability, the toner described above is likely tohave a lowered resin strength. As a result, various disadvantages aremore likely to take place, such as a disadvantage concerning thelowering of durability caused by deposition on a developer blade orgeneration of filming on a photoconductor when a toner is applied with alarger mechanical or thermal stress due to the speeding-up andminiaturization, and a disadvantage in fall-off of toner, which is aphenomenon in which toners are dropped off from a developer roller.These disadvantages are especially serious when a toner is applied to anonmagnetic monocomponent developer device in which toners are chargedby frictional forces with a developer blade, or when a toner is appliedto an oil-less nonmagnetic monocomponent developer device in which areleasing agent must be contained in the toner in a large amount.

In view of these disadvantages, a method for producing a toner includingthe steps of melt-kneading a crystalline polyester and an amorphousresin, and heat-treating a melt-kneaded mixture to obtain a toner whichsatisfies all of low-temperature fixing ability, storage property, anddurability is proposed (see JP-A-2005-308995 (US-A-2007/207401) andJP-A-2009-116175 (US-A-2009/116175)).

In addition, a toner containing a resin binder containing a blockcopolymer or a graft copolymer obtained by chemically bonding 3 to 50parts by weight of a crystalline polyester and 97 to 50 parts by weightof an ionically cross-linked amorphous vinyl polymer, wherein achloroform-insoluble content is from 3 to 10% by weight of the copolymeris shown to have excellent offset resistance and low-temperature fixingability (see JP-A-Hei-4-81770).

As a method of improving fall-off of a toner, a method including thestep of adding fine magnesium silicate compound particlessurface-treated with a fatty acid to a toner as an external additive isproposed (see JP-A-2007-240716 (US-A-2007/190443)).

SUMMARY OF THE INVENTION

The present invention relates to a method for producing a tonerincluding the steps of:

melt-kneading at least a resin binder and a colorant to give a kneadedproduct (step 1); and

heat-treating the kneaded product obtained in the step 1 (step 2),

wherein the resin binder contains a crystalline resin and an amorphousresin, wherein the crystalline resin contains a composite resincontaining:(a) a polycondensation resin component obtained by polycondensing analcohol component containing an aliphatic diol having 2 to 10 carbonatoms and a carboxylic acid component containing an aromaticdicarboxylic acid compound, and(b) a styrenic resin component,wherein a weight ratio of the polycondensation resin component to thestyrenic resin component in the composite resin, i.e. polycondensationresin component/styrenic resin component, is from 50/50 to 95/5, andwherein the composite resin is contained in an amount of from 5 to 40%by weight of the resin binder.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method for producing a toner havingexcellent low-temperature fixing ability, and excellent durability, morespecifically, no generation of filming on a photoconductor duringdurability printing, and further suppressed fall-off of a toner, inother words suppressed dropping of a toner off a developer roller.Further, the present invention relates to a method for producing a tonerhaving a shorter heat-treating time, thereby having high productivity.

The toner obtained by the method of the present invention exhibits someeffects of having excellent low-temperature fixing ability, and showingsuppressed properties in filming on a photoconductor and fall-off of atoner. The toner described above also exhibits excellent effects evenwhen applied to a nonmagnetic monocomponent developer device, andespecially when applied to an oil-less nonmagnetic monocomponentdeveloper device that necessitates a toner to contain a releasing agentin a larger amount. Further, the method of the present invention is amethod for producing a toner having shorter time period for aheat-treating step, thereby having a high productivity.

These and other advantages of the present invention will be apparentfrom the following description.

Conventional methods have some disadvantages that a long period of heattreatment would be necessitated, thereby lowering productivity, wherebycausing insufficient suppression in filming of the toner on aphotoconductor and fall-off of the toner.

The method for producing a toner of the present invention is a methodfor producing a toner, including the steps of:

melt-kneading at least a resin binder and a colorant to give a kneadedproduct (step 1); and

heat-treating the kneaded product obtained in the step 1 (step 2),

wherein the great feature of the present invention is in that the resinbinder contains an amorphous resin and a crystalline resin, wherein thecrystalline resin contains a composite resin containing:(a) a polycondensation resin component obtained by polycondensing analcohol component containing an aliphatic diol having 2 to 10 carbonatoms and a carboxylic acid component containing an aromaticdicarboxylic acid compound, and(b) a styrenic resin component.Accordingly, the toner obtained by the method of the present inventionexhibits some effects of showing excellent low-temperature fixingability, and suppression in filming of the toner on a photoconductor andfall-off of the toner.

The detailed reasons why the effects of the present invention areexhibited are not elucidated. Although not wanting to be limited bytheory, it is presumably due to the fact that a crystalline compositeresin in the present invention is more likely to be dispersed in theresin binder, so that crystals are homogeneously and finely dispersed inthe resin binder. Further, a styrenic resin component is more easilylikely to form a phase separation structure with the polycondensationresin component during the heat treatment. As a result, the crystals areallowed to grow in a short time period in the heat-treating step. Inaddition, since the crystals are homogenously and finely dispersed inthe resin binder, it is considered that the resulting toner satisfiesboth low-temperature fixing ability and durability such as suppressionin filming of the toner on a photoconductor. Furthermore, since thecomposite resin contains a styrenic resin component, an effect ofenhancing triboelectric stability is also added, so that it is thoughtthat an effect of suppression in fall-off of the toner is exhibited.

In the present invention, it is preferable that the resin bindercontains an amorphous resin and a crystalline resin, wherein thecrystalline resin mainly contains a composite resin containing:

(a) a polycondensation resin component obtained by polycondensing analcohol component containing an aliphatic diol having 2 to 10 carbonatoms and a carboxylic acid component containing an aromaticdicarboxylic acid compound, and(b) a styrenic resin component,from the viewpoint of improvement in low-temperature fixing ability, andsuppression in filming on a photoconductor or fall-off of the toner.

Here, the crystallinity of the resin is expressed by a crystallinityindex defined by a value of a ratio of a softening point to atemperature of maximum endothermic peak determined by a scanningdifferential calorimeter, i.e. softening point/temperature of maximumendothermic peak. The crystalline resin is a resin having acrystallinity index of from 0.6 to 1.4, preferably from 0.7 to 1.2, andmore preferably from 0.9 to 1.2, and the amorphous resin is a resinhaving a crystallinity index exceeding 1.4 or less than 0.6. Thecrystallinity of the resin can be adjusted by the kinds of the rawmaterial monomers, a ratio thereof, production conditions (for example,reaction temperature, reaction time, cooling rate), and the like. Here,the temperature of maximum endothermic peak refers to a temperature ofthe peak on the highest temperature side among endothermic peaksobserved. When a difference between the temperature of maximumendothermic peak and the softening point is within 20° C., thetemperature of maximum endothermic peak is defined as a melting point.When the difference between the temperature of maximum endothermic peakand the softening point exceeds 20° C., the peak is a peak ascribed to aglass transition.

In the present invention, the polycondensation resin componentconstituting the composite resin is a resin obtained by polycondensingan alcohol component containing an aliphatic diol having 2 to 10 carbonatoms and a carboxylic acid component containing an aromaticdicarboxylic acid compound, from the viewpoint of improvement inlow-temperature fixing ability of toner, and suppression in filming on aphotoconductor and fall-off of the toner.

The polycondensation resin component includes polyesters,polyester-polyamides, and the like, and the polyesters are preferred,from the viewpoint of low-temperature fixing ability of the toner.

In the present invention, the alcohol component of the polycondensationresin component contains an aliphatic diol having 2 to 10 carbon atoms,preferably 4 to 8 carbon atoms, and more preferably 4 to 6 carbon atoms,from the viewpoint of enhancement of crystallinity of the compositeresin.

The aliphatic diol having 2 to 10 carbon atoms includes ethylene glycol,1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol,1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol,1,9-nonanediol, neopentyl glycol, 1,4-butenediol, and the like.Especially, from the viewpoint of enhancement of crystallinity of thecomposite resin, the α,ω-linear alkanediol is preferred, 1,4-butanedioland 1,6-hexanediol are more preferred, and 1,6-hexanediol is even morepreferred.

The aliphatic diol having 2 to 10 carbon atoms is contained in an amountof preferably 70% by mol or more, more preferably from 80 to 100% bymol, and even more preferably from 90 to 100% by mol, of the alcoholcomponent, from the viewpoint of enhancement of crystallinity of thecomposite resin. Especially, a proportion of one kind of the aliphaticdiol having 2 to 10 carbon atoms occupying the alcohol component ispreferably 50% by mol or more, and more preferably from 60 to 100% bymol, of the alcohol component.

The alcohol component may contain a polyhydric alcohol component otherthan the aliphatic diol having 2 to 10 carbon atoms, and the polyhydricalcohol component includes aromatic diols such as an alkylene oxideadduct of bisphenol A, represented by the formula (I):

wherein RO and OR are an oxyalkylene group, wherein R is an ethyleneand/or propylene group, x and y each shows the number of moles of thealkylene oxide added, each being a positive number, and the sum of x andy on average is preferably from 1 to 16, more preferably from 1 to 8,and even more preferably from 1.5 to 4; andtrihydric or higher polyhydric alcohols such as glycerol,pentaerythritol, trimethylolpropane, sorbitol, and 1,4-sorbitan.

In the present invention, the carboxylic acid component of thepolycondensation resin component contains an aromatic dicarboxylic acidcompound, from the viewpoint of suppression in fall-off of a toner.

The aromatic dicarboxylic acid compound is preferably those having 8 to12 carbon atoms, including aromatic dicarboxylic acids, such as phthalicacid, isophthalic acid, and terephthalic acid, and acid anhydridesthereof and alkyl (1 to 8 carbon atoms) esters thereof. Here, thedicarboxylic acid compound refers to a dicarboxylic acid, an acidanhydride thereof, and an alkyl (1 to 8 carbon atoms) ester thereof,among which the dicarboxylic acids are preferred. In addition, thepreferred number of carbon atoms means the number of carbon atoms of thedicarboxylic acid moiety of the dicarboxylic acid compound.

The aromatic dicarboxylic acid compound is contained in an amount ofpreferably from 70 to 100% by mol, and more preferably from 90 to 100%by mol, of the carboxylic acid component, from the viewpoint ofsuppression in fall-off of a toner.

The carboxylic acid component may contain a polycarboxylic acid compoundother than the aromatic dicarboxylic acid compound. The polycarboxylicacid compound includes aliphatic dicarboxylic acids, such as oxalicacid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconicacid, glutaconic acid, succinic acid, adipic acid, and succinic acidssubstituted with an alkyl group having 1 to 30 carbon atoms or analkenyl group having 2 to 30 carbon atoms; alicyclic dicarboxylic acidssuch as cyclohexanedicarboxylic acid; aromatic, tricarboxylic or higherpolycarboxylic acids, such as trimellitic acid,2,5,7-naphthalenetricarboxylic acid, and pyromellitic acid; acidanhydrides thereof, and alkyl(1 to 8 carbon atoms) esters thereof.

Here, in the present specification, a dually reactive monomer describedlater is not counted to be included in the amount of the alcoholcomponent or the carboxylic acid component contained.

The total number of moles of the aromatic dicarboxylic acid compound andthe aliphatic diol having 2 to 10 carbon atoms is preferably from 75 to100% by mol, more preferably from 85 to 100% by mol, and even morepreferably from 95 to 100% by mol, of the total number of moles of theraw material components of the polycondensation resin component, i.e.the carboxylic acid component and the alcohol component, from theviewpoint of enhancement of crystallinity of the composite resin andfrom the viewpoint of suppression in fall-off of a toner.

As to the molar ratio of the carboxylic acid component to the alcoholcomponent in the polycondensation resin component, i.e. carboxylic acidcomponent/alcohol component, in order to achieve a larger molecularweight of the composite resin, it is preferable that the proportion ofthe alcohol component is greater than the carboxylic acid component, andthe molar ratio is more preferably from 0.50 to 0.89, and even morepreferably from 0.70 to 0.85.

The polycondensation reaction of the raw material monomers for thepolycondensation resin component can be carried out by polymerizing theraw material monomers in an inert gas atmosphere at a temperature offrom 180° to 250° C. or so, optionally in the presence of anesterification catalyst, a polymerization inhibitor or the like. Theesterification catalyst includes tin compounds such as dibutyltin oxideand tin(II) 2-ethylhexanoate; titanium compounds such as titaniumdiisopropylate bistriethanolaminate; and the like. The esterificationpromoter that can be used together with the esterification catalystincludes gallic acid, and the like. The esterification catalyst is usedin an amount of preferably from 0.01 to 1.5 parts by weight, and morepreferably from 0.1 to 1.0 part by weight, based on 100 parts by weightof a total amount of the alcohol component, the carboxylic acidcomponent, and the dually reactive monomer component. The esterificationpromoter is used in an amount of preferably from 0.001 to 0.5 parts byweight, and more preferably from 0.01 to 0.1 parts by weight, based on100 parts by weight of a total amount of the alcohol component, thecarboxylic acid component, and the dually reactive monomer component.

As the raw material monomers for the styrenic resin component, styreneor styrene derivatives such as α-methylstyrene and vinyltoluene(hereinafter, the styrene and styrene derivatives are collectivelyreferred to as “styrenic derivatives”) are used.

The styrenic derivative is contained in an amount of preferably 70% byweight or more, more preferably 80% by weight or more, and even morepreferably 90% by weight or more, of the raw material monomers for thestyrenic resin component, from the viewpoint of improvement intriboelectric charges of a toner, and suppression in filming on aphotoconductor and fall-off of a toner.

The raw material monomers for the styrenic resin component that areusable other than the styrenic derivative include alkyl (meth)acrylateester; ethylenically unsaturated monoolefins, such as ethylene andpropylene; diolefins such as butadiene; halovinyls such as vinylchloride; vinyl esters such as vinyl acetate and vinyl propionate;ethylenically monocarboxylate esters such as dimethylaminoethyl(meth)acrylate; vinyl ethers such as vinyl methyl ether; vinylidenehalides such as vinylidene chloride; N-vinyl compounds such asN-vinylpyrrolidone; and the like.

The raw material monomers for the styrenic resin component that areusable other than the styrenic derivative can be used in a combinationof two or more kinds. The term “(meth)acrylic acid” as used herein meansacrylic acid and/or methacrylic acid.

Among the raw material monomers for the styrenic resin component thatare usable other than the styrenic derivative, the alkyl (meth)acrylateester is preferred, from the viewpoint of improving low-temperaturefixing ability of the toner. The alkyl group in the alkyl (meth)acrylateester has preferably 1 to 22 carbon atoms, and more preferably 8 to 18carbon atoms, from the viewpoint mentioned above. Here, the number ofcarbon atoms of the alkyl ester refers to the number of carbon atomsderived from the alcohol component moiety constituting the ester.

Specific examples of the alkyl (meth)acrylate ester includes methyl(meth)acrylate, ethyl (meth)acrylate, (iso)propyl (meth)acrylate,2-hydroxyethyl (meth)acrylate, (iso or tert)butyl (meth)acrylate,2-ethylhexyl (meth)acrylate, (iso)octyl (meth)acrylate, (iso)decyl(meth)acrylate, (iso)stearyl (meth)acrylate, and the like. Here, theexpression “(iso or tert)” or “(iso)” embrace both a case where thesegroups are present and a case where the groups are absent, and the casewhere the groups are absent means normal. Also, the expression“(meth)acrylate” means that both cases of acrylate and methacrylate areincluded.

The alkyl (meth)acrylate ester is contained in an amount of preferably30% by weight or less, more preferably 20% by weight or less, and evenmore preferably 10% by weight or less, of the raw material monomers forthe styrenic resin component, from the viewpoint of suppression infilming of a toner on a photoconductor and fall-off of a toner.

Here, a resin obtained by addition polymerization of raw materialmonomers containing a styrenic derivative and an alkyl (meth)acrylateester is also referred to as styrene-(meth)acrylate resin.

The addition polymerization reaction of the raw material monomers forthe styrenic resin component can be carried out by a conventionalmethod, for example, a method of carrying out the reaction of the rawmaterial monomers in the presence of a polymerization initiator such asdicumyl peroxide, a crosslinking agent, and the like in an organicsolvent or without any solvents. The temperature conditions arepreferably from 110° to 200° C., and more preferably from 140° to 170°C.

When an organic solvent is used upon the addition polymerizationreaction, xylene, toluene, methyl ethyl ketone, acetone, or the like canbe used. It is preferable that the organic solvent is used in an amountof from 10 to 50 parts by weight or so, based on 100 parts by weight ofthe raw material monomers for the styrenic resin component.

The styrenic resin component has a glass transition temperature (Tg) ofpreferably from 60° to 130° C., more preferably from 80° to 120° C., andeven more preferably from 90° to 110° C., from the viewpoint ofimprovement in low-temperature fixing ability of a toner and suppressionin filming on a photoconductor or fall-off of a toner.

As to Tg of the styrenic resin component, a value obtained by acalculation based on Tgn of a homopolymer of each of the monomersconstituting each polymer, in accordance with Fox formula (T. G. Fox,Bull. Am. Physics Soc., 1(3), 123 (1956)), an empirical formula forpredicting Tg by a thermal additive formula in a case of a polymer, isused as calculated from the following formula (1):

1/Tg=Σ(Wn/Tgn)  (1)

wherein Tgn is Tg expressed in absolute temperature for a homopolymer ofeach of the components; and Wn is a weight percentage of each of thecomponents.

The dually reactive monomer described later as used herein is assumednot to be counted in the calculation for the amount of the styrenicresin component contained, and not included in the calculation for Tg ofthe styrenic resin component.

In the calculation of the glass transition temperature (Tg) according tothe Fox formula usable in Examples of the present invention, Tgn ofstyrene of 373 K (100° C.) and Tgn of 2-ethylhexyl acrylate of 223 K(−50° C.) are used.

It is preferable in the composite resin that the polycondensation resincomponent and the styrenic resin component are bonded directly or via alinking group. The linking group includes dually reactive monomersdescribed later, compounds derived from chain transfer agents, and otherresins, and the like.

The composite resin is preferably in a state that the polycondensationresin component and the styrenic resin component mentioned above aredispersed in each other, and the dispersion state mentioned above can beevaluated by a difference between Tg of the composite resin measured bythe method described in Examples and a calculated value according to theabove Fox formula.

In other words, while the composite resin in the present invention is acrystalline resin, the composite resin contains an amorphous portionderived from the styrenic resin component and the polycondensation resincomponent, so that the composite resin has a Tg ascribed to the styrenicresin component and a Tg ascribed to the polycondensation resincomponent. The Tg of the styrenic resin component and the Tg of thepolycondensation resin component in the composite resin are values foundseparately. The higher the degree of dispersion of the styrenic resincomponent and the polycondensation resin component, the more approximatethe both Tg values to each other; therefore, when the styrenic resincomponent and the polycondensation resin component are dispersed into anearly homogenous state, both the Tg's overlap, and the found valueswould be nearly one.

Therefore, in the state where the styrenic resin component and thepolycondensation resin component are dispersed in each other, the Tg ofthe composite resin measured under the measurement conditions describedlater takes a value different from a Tg calculated according to the Foxformula for the styrenic resin component mentioned above. Specifically,the absolute value of a difference in a glass transition temperature ofthe composite resin and a glass transition temperature of the styrenicresin component of the composite resin calculated according to Foxformula is preferably 10° C. or more, more preferably 30° C. or more,even more preferably 50° C. or more, and even more preferably 70° C. ormore. In general, since the polycondensation resin component has a Tglower than Tg of the styrenic resin component, the found values for theTg of the composite resin may be lower than calculated values of Tg ofthe styrenic resin in many cases.

The composite resin as describe above can, for example, be obtained by:

(1) a method including the step of polycondensing raw material monomersfor a polycondensation resin component in the presence of a styrenicresin having a carboxyl group or a hydroxyl group, wherein the carboxylgroup or the hydroxyl group includes those derived from a duallyreactive monomer or a chain transfer agent described later;(2) a method including the step of subjecting raw material monomers fora styrenic resin component to addition polymerization in the presence ofa polycondensation resin having a reactive unsaturated bond; or thelike.

It is preferable that the composite resin is a resin obtained from theraw material monomers for the polycondensation resin component and theraw material monomers for the styrenic resin component, and further adually reactive monomer, capable of reacting with both of the rawmaterial monomers for the polycondensation resin component and the rawmaterial monomers for the styrenic resin component (hybrid resin), fromthe viewpoint of improvement in low-temperature fixing ability of thetoner, and suppression in filming of the toner on a photoconductor andfall-off of the toner, and from the viewpoint of an increase inproductivity. Therefore, upon the polymerization of the raw materialmonomers for the polycondensation resin component and the raw materialmonomers for the styrenic resin component to obtain a composite resin,it is preferable that the polycondensation reaction and/or the additionpolymerization reaction is carried out in the presence of the duallyreactive monomer. By inclusion of the dually reactive monomer, thecomposite resin is a resin formed by binding the polycondensation resincomponent and the styrenic resin component via a constituting unitderived from the dually reactive monomer (hybrid resin), in which thepolycondensation resin component and the styrenic resin component aremore finely and homogeneously dispersed.

From the viewpoints, it is preferable that the composite resin is aresin obtained by polymerizing:

(i) raw material monomers for the polycondensation resin component,containing an alcohol component containing an aliphatic diol having 2 to10 carbon atoms and a carboxylic acid component containing an aromaticdicarboxylic acid compound;(ii) raw material monomers for the styrenic resin component; and(iii) a dually reactive monomer capable of reacting with both of the rawmaterial monomers for the polycondensation resin component and the rawmaterial monomers for the styrenic resin component.

It is preferable that the dually reactive monomer is a compound havingin its molecule at least one functional group selected from the groupconsisting of a hydroxyl group, a carboxyl group, an epoxy group, aprimary amino group and a secondary amino group, preferably a carboxylgroup and/or a hydroxyl group, and more preferably a carboxyl group, andan ethylenically unsaturated bond. By using the dually reactive monomerdescribed above, dispersibility of the resin forming a dispersion phasecan be even more improved. It is preferable that the dually reactivemonomer is at least one member selected from the group consisting ofacrylic acid, methacrylic acid, fumaric acid, maleic acid, and maleicanhydride. It is more preferable that the dually reactive monomer isacrylic acid, methacrylic acid, or fumaric acid, from the viewpoint ofreactivities of the polycondensation reaction and the additionpolymerization reaction. Here, in a case where a polymerizationinhibitor is used together with the dually reactive monomer, apolycarboxylic acid such as fumaric acid may function as raw materialmonomers for the polycondensation resin component in some cases.

From the viewpoint of enhancement of dispersibility of the styrenicresin component and the polycondensation resin component, improvement inlow-temperature fixing ability of the toner, and suppression in filmingon a photoconductor or fall-off of a toner, and from the viewpoint ofincrease in productivity of the toner, the dually reactive monomer isused in an amount of preferably from 1 to 30 mol, more preferably from 2to 25 mol, and even more preferably from 2 to 20 mol, based on 100 molof a total of the alcohol component of the polycondensation resincomponent, and the dually reactive monomer is used in an amount ofpreferably from 2 to 30 mol, more preferably from 5 to 25 mol, and evenmore preferably from 10 to 20 mol, based on a total of 100 mol of theraw material monomers for the styrenic resin component, not including apolymerization initiator.

Specifically, it is preferable that the composite resin is produced bythe following method. It is preferable that the dually reactive monomeris used in the addition polymerization reaction together with the rawmaterial monomers for the styrenic resin component, from the viewpointof improvement in low-temperature fixing ability of the toner, andsuppression in filming on a photoconductor or fall-off of the toner.

(i) Method including the steps of (A) carrying out a polycondensationreaction of raw material monomers for a polycondensation resincomponent; and thereafter (B) carrying out an addition polymerizationreaction of raw materials monomers for a styrenic resin component and adually reactive monomer

In this method, the step (A) is carried out under reaction temperatureconditions appropriate for a polycondensation reaction, a reactiontemperature is then lowered, and the step (B) is carried out undertemperature conditions appropriate for an addition polymerizationreaction. It is preferable that the raw material monomers for thestyrenic resin component and the dually reactive monomer are added to areaction system at a temperature appropriate for an additionpolymerization reaction. The dually reactive monomer also reacts withthe polycondensation resin component as well as in the additionpolymerization reaction.

After the step (B), a reaction temperature is raised again, raw materialmonomers for a polycondensation resin component such as a trivalent orhigher polyvalent monomer serving as a crosslinking agent is optionallyadded to the polymerization system, whereby the polycondensationreaction of the step (A) and the reaction with the dually reactivemonomer can be further progressed.

(ii) Method including the steps of (B) carrying out an additionpolymerization reaction of raw materials monomers for a styrenic resincomponent and a dually reactive monomer, and thereafter (A) carrying outa polycondensation reaction of raw material monomers for apolycondensation resin component

In this method, the step (B) is carried out under reaction temperatureconditions appropriate for an addition polymerization reaction, areaction temperature is then raised, and the step (A) a polycondensationreaction is carried out under reaction temperature conditionsappropriate for the polycondensation reaction. The dually reactivemonomer is also involved in a polycondensation reaction as well as theaddition polymerization reaction.

The raw materials for the polycondensation resin component may bepresent in a reaction system during the addition polymerizationreaction, or the raw materials for the polymerization resin componentmay be added to a reaction system under temperatures conditionsappropriate for the polycondensation reaction. In the former case, theprogress of the polycondensation reaction can be adjusted by adding anesterification catalyst at a temperature appropriate for thepolycondensation reaction.

(iii) Method including the steps of concurrently carrying out the step(A) a polycondensation reaction of raw material monomers for apolycondensation resin component; and the step (B) an additionpolymerization reaction of raw materials monomers for a styrenic resincomponent and a dually reactive monomer

In this method, it is preferable that the steps (A) and (B) are carriedout under reaction temperature conditions appropriate for an additionpolymerization reaction, a reaction temperature is raised, raw materialmonomers for the polycondensation resin component of a trivalent orhigher polyvalent monomer are optionally added to a polymerizationsystem, and the polycondensation reaction of the step (A) is furthercarried out. During the process, the polycondensation reaction alone canalso be progressed by adding a radical polymerization inhibitor undertemperature conditions appropriate for the polycondensation reaction.The dually reactive monomer is also involved in a polycondensationreaction as well as the addition polymerization reaction.

In the above method (i), a polycondensation resin that is previouslypolymerized may be used in place of the step (A) of carrying out apolycondensation reaction. In the above method (iii), when the steps (A)and (B) are concurrently carried out, a mixture containing raw materialmonomers for the styrenic resin component can be added dropwise to amixture containing raw material monomers for the polycondensation resincomponent to react.

It is preferable that the above methods (i) to (iii) are carried out inthe same vessel.

In the composite resin, a weight ratio of the polycondensation resincomponent to the styrenic resin component [polycondensation resincomponent/styrenic resin component] (in the present invention, theweight ratio is defined as a weight ratio of the raw material monomersfor the polycondensation resin component to the raw material monomersfor the styrenic resin component, without including a polymerizationinitiator in the raw material monomers for the styrenic resincomponent), more specifically a total amount of the raw materialmonomers for the polycondensation resin component/a total amount of theraw material monomers for the styrenic resin component, is from 50/50 to95/5, preferably from 70/30 to 95/5, and more preferably from 70/30 to90/10, from the viewpoint of improvement in low-temperature fixingability of the toner and suppression in fall-off of the toner, and fromthe viewpoint of increase in productivity of the toner, so as to providea continuous phase composed of the polycondensation resin and adispersed phase composed of a styrenic resin. Here, in the abovecalculation, the amount of the dually reactive monomer is included inthe raw material monomers for the polycondensation resin component.

In order to obtain a composite resin that has a large molecular weight,reaction conditions, such as adjustment of a molar ratio of thecarboxylic acid component to the alcohol component as mentioned above,elevation of a reaction temperature, increase in the amount of acatalyst, and a dehydration reaction being carried out for a long periodof time under a reduced pressure, may be selected. Here, a crystallineresin having a large molecular weight can also be produced by stirring areaction raw material mixture with a high-output motor, and when acrystalline resin is produced without specifically selecting productionfacilities, a method including the step of reacting raw materialmonomers in the presence of a non-reactive low-viscosity resin and asolvent is also an effective means.

The composite resin has a softening point of preferably 80° C. orhigher, more preferably 100° C. or higher, and even more preferably 110°C. or higher, from the viewpoint of suppression in filming of a toner ona photoconductor and fall-off of a toner. The composite resin has asoftening point of preferably 160° C. or lower, more preferably 140° C.or lower, and even more preferably 135° C. or lower, from the viewpointof improvement in low-temperature fixing ability of the toner. Takentogether these viewpoints, the composite resin has a softening point ofpreferably from 80° to 160° C., more preferably from 100° to 140° C.,even more preferably from 100° to 135° C., and even more preferably from110° to 135° C.

In addition, the composite resin has a melting point, i.e. a temperatureof the maximum endothermic peak, of preferably 80° C. or higher, morepreferably 100° C. or higher, and even more preferably 120° C. orhigher, from the viewpoint of suppression in filming of the toner on aphotoconductor or fall-off of the toner. In addition, the compositeresin has a melting point of preferably 150° C. or lower, morepreferably 140° C. or lower, and even more preferably 130° C. or lower,from the viewpoint of improvement in low-temperature fixing ability ofthe toner. Taken together these viewpoints, the composite resin has amelting point of preferably from 80° to 150° C., more preferably from100° to 140° C., and even more preferably from 120° to 130° C.

The softening point and the melting point can be adjusted by controllinga raw material monomer composition, a polymerization initiator, amolecular weight, an amount of a catalyst, or the like, or selectingreaction conditions.

In addition, the composite resin has a Tg of preferably −10° C. orhigher, more preferably −5° C. or higher, and even more preferably 0° C.or higher, from the viewpoint of suppression in filming of the toner ona photoconductor or fall-off of the toner. Also, the composite resin hasa Tg of preferably 50° C. or lower, more preferably 40° C. or lower, andeven more preferably 30° C. or lower, from the viewpoint of improvementin low-temperature fixing ability of the toner. Taken together theseviewpoints, the composite resin has a Tg of preferably from −10° to 50°C., more preferably from −5° to 40° C., and even more preferably from 0°to 30° C.

In the present invention, the crystalline resin may contain acrystalline polyester or the like. The composite resin mentioned aboveis contained in an amount of preferably 80% by weight or more, morepreferably 90% by weight or more, and even more preferably 95% by weightor more, of the crystalline resin, from the viewpoint of improvement inlow-temperature fixing ability of the toner, and suppression in filmingof the toner on a photoconductor or fall-off of the toner.

The composite resin is contained in an amount of 5% by weight or more,preferably 7% by weight or more, and more preferably 8% by weight ormore, of the resin binder, from the viewpoint of improvement inlow-temperature fixing ability of the toner and suppression in fall-offof the toner. Also, the composite resin is contained in an amount of 40%by weight or less, preferably 30% by weight or less, more preferably 25%by weight or less, and even more preferably 15% by weight or less, ofthe resin binder, from the viewpoint of suppression in filming of thetoner on a photoconductor or fall-off of the toner. Taken together theseviewpoints, the composite resin is contained in an amount of from 5 to40% by weight, preferably from 5 to 30% by weight, more preferably from7 to 25% by weight, and even more preferably from 8 to 15% by weight, ofthe resin binder.

As the amorphous resin in the present invention, a polyester, a vinylresin, an epoxy resin, a polycarbonate, a polyurethane, or the like isused. The amorphous resin is preferably a polyester obtained bypolycondensation of an alcohol component and a carboxylic acidcomponent, from the viewpoint of improvement in low-temperature fixingability of the toner, and suppression in filming of the toner on aphotoconductor or fall-off of the toner.

It is preferable that the amorphous polyester usable in the presentinvention is a polyester obtained by polycondensation of an alcoholcomponent containing 70% by mol or more of an alkylene oxide adduct ofbisphenol A represented by the above formula (I), and a carboxylic acidcomponent, from the viewpoint of suppression in fall-off of the toner.

The alkylene oxide adduct of bisphenol A mentioned above is contained inan amount of preferably 70% by mol or more, more preferably from 80 to100% by mol, and even more preferably from 90 to 100% by mol, of thealcohol component, from the viewpoint of suppression in fall-off of thetoner.

The alcohol component other than the alkylene oxide adduct of bisphenolA include the polyhydric alcohols similar to those usable for thecrystalline resin mentioned above.

The carboxylic acid component preferably contains the aromaticdicarboxylic acid compound mentioned above, and more preferablyterephthalic acid, from the viewpoint of suppression in fall-off of thetoner. The aromatic dicarboxylic acid compound is contained in an amountof preferably from 30 to 100% by mol, more preferably from 50 to 100% bymol, and even more preferably from 60 to 100% by mol, of the carboxylicacid component.

The polycarboxylic acid compounds that can be used other than thearomatic dicarboxylic acid compound include the polycarboxylic acidcompounds similar to those usable for the crystalline resin.

The amorphous polyester can be produced by, for example, polycondensingan alcohol component and a carboxylic acid component in an inert gasatmosphere at a temperature of from 180° to 250° C. or so, optionally inthe presence of an esterification catalyst, a polymerization inhibitoror the like. The esterification catalyst includes tin compounds such asdibutyltin oxide and tin(II) 2-ethylhexanoate; titanium compounds suchas titanium diisopropylate bistriethanolaminate; and the like. Theesterification promoter includes gallic acid, and the like. Theesterification catalyst is used in an amount of preferably from 0.01 to1 part by weight, and more preferably from 0.1 to 0.6 parts by weight,based on 100 parts by weight of a total amount of the alcohol componentand the carboxylic acid component. The esterification promoter is usedin an amount of preferably from 0.001 to 0.5 parts by weight, and morepreferably from 0.01 to 0.1 parts by weight, based on 100 parts byweight of a total amount of the alcohol component and the carboxylicacid component.

The amorphous polyester has an acid value of preferably 30 mg KOH/g orless, more preferably 25 mg KOH/g or less, and even more preferably 20mg KOH/g or less, from the viewpoint of improvement in transferabilityof the toner.

In the present invention, the amorphous polyester containing a polyestercomponent obtained by polycondensing an alcohol component and acarboxylic acid component includes not only polyesters but also modifiedresins thereof.

The modified resin of the polyesters includes, for example,urethane-modified polyesters in which the polyesters are modified with aurethane bond, epoxy-modified polyesters in which the polyesters aremodified with an epoxy bond, a hybrid resin in which a polyestercomponent and other resin component are formed into a composite, and thelike.

The amorphous resin has a softening point of preferably 70° C. orhigher, and more preferably 90° C. or higher, from the viewpoint offilming of the toner on a photoconductor and suppression in fall-off ofthe toner. Also, the amorphous resin has a softening point of preferably180° C. or lower, and more preferably 150° C. or lower, from theviewpoint of improvement in low-temperature fixing ability of the toner.Taken together these viewpoints, the amorphous resin has a softeningpoint of preferably from 70° to 180° C., and more preferably from 90° to150° C.

It is preferable that the amorphous resin is composed of two kinds ofpolyesters, i.e. a low-softening point polyester and a high-softeningpoint polyester, of which softening points are different by preferably5° C. or higher, and more preferably by 10° to 50° C., from theviewpoint of improvement in low-temperature fixing ability of the toner,and from the viewpoint of suppression in filming of the toner on aphotoconductor and fall-off of the toner. The low-softening pointpolyester has a softening point of preferably from 80° to 125° C., andmore preferably from 85° to 120° C., from the viewpoint oflow-temperature fixing ability, and the high-softening point polyesterhas a softening point of preferably from 110° to 150° C., and morepreferably from 115° to 145° C., from the viewpoint of suppression infilming of the toner on a photoconductor or fall-off of the toner. Theweight ratio of the high-softening point resin to the low-softeningpoint resin, i.e. high-softening point resin/low-softening point resin,is preferably from 10/90 to 90/10, and more preferably from 20/80 to80/20, from the viewpoint of improvement in low-temperature fixingability of the toner, and suppression in filming of the toner on aphotoconductor or fall-off of the toner.

The amorphous resin has a Tg of preferably 45° C. or higher, and morepreferably 55° C. or higher, from the viewpoint of suppression infilming of the toner on a photoconductor or fall-off of the toner. Also,the amorphous resin has a Tg of preferably 80° C. or lower, and morepreferably 75° C. or lower, from the viewpoint of improvement inlow-temperature fixing ability of the toner. Taken together theseviewpoints, the amorphous resin has a Tg of preferably from 45° to 80°C., and more preferably from 55° to 75° C. Here, Tg is a physicalproperty peculiarly owned by the amorphous phase, which is distinguishedfrom a temperature of the maximum endothermic peak.

The weight ratio of the crystalline resin to the amorphous resin, i.e.crystalline resin/amorphous resin, is preferably from 5/95 to 40/60,more preferably from 5/95 to 30/70, and even more preferably from 8/92to 20/80, from the viewpoint of improvement in low-temperature fixingability of the toner, and suppression in filming of the toner on aphotoconductor or fall-off of the toner.

As the colorant, all of the dyes, pigments and the like which are usedas colorants for toners can be used, and carbon blacks, PhthalocyanineBlue, Permanent Brown FG, Brilliant Fast Scarlet, Pigment Green B,Rhodamine-B Base, Solvent Red 49, Solvent Red 146, Solvent Blue 35,quinacridone, carmine 6B, isoindoline, disazo yellow, or the like can beused. The colorant is contained in an amount of preferably from 1 to 40parts by weight, and more preferably from 2 to 10 parts by weight, basedon 100 parts by weight of the resin binder. The toner in the presentinvention may be any of black toners and color toners.

The toner in the present invention may contain, in addition to the resinbinder and the colorant, a releasing agent, a charge control agent, orthe like.

The releasing agent includes aliphatic hydrocarbon waxes such aslow-molecular weight polypropylenes, low-molecular weight polyethylenes,low-molecular weight polypropylene-polyethylene copolymers,microcrystalline waxes, paraffinic waxes, and Fischer-Tropsch wax, andoxides thereof; ester waxes such as carnauba wax, montan wax, and sazolewax, and deacidified waxes thereof, and fatty acid ester waxes; fattyacid amides, fatty acids, higher alcohols, metal salts of fatty acids,and the like. These releasing agents may be used alone or in a mixtureof two or more kinds.

The releasing agent has a melting point of preferably from 60° to 160°C., and more preferably from 60° to 150° C., from the viewpoint oflow-temperature fixing ability and offset resistance of the toner.

The releasing agent is contained in an amount of preferably 10 parts byweight or less, more preferably 8 parts by weight or less, and even morepreferably 7 parts by weight or less, based on 100 parts by weight ofthe resin binder, from the viewpoint of preventing filming of the toneron a photoconductor. Also, the releasing agent is contained in an amountof preferably 0.5 parts by weight or more, more preferably 1.0 part byweight or more, and even more preferably 1.5 parts by weight or more,based on 100 parts by weight of the resin binder, from the viewpoint ofimprovement in high-temperature offset resistance of the toner.Therefore, taken together these viewpoints, the releasing agent iscontained in an amount of preferably from 0.5 to 10 parts by weight,more preferably from 1.0 to 8 parts by weight, and even more preferablyfrom 1.5 to 7 parts by weight, based on 100 parts by weight of the resinbinder. In addition, the releasing agent is contained in an amount ofpreferably 3 parts by weight or more, more preferably 3.5 parts byweight or more, and even more preferably 4 parts by weight or more,based on 100 parts by weight of the resin binder, from the viewpoint ofeffecting oil-less fusing of the toner. Therefore, taken together theseviewpoints, the releasing agent is contained in an amount of preferablyfrom 3 to 10 parts by weight, more preferably from 3.5 to 8 parts byweight, and even more preferably from 4 to 7 parts by weight, based on100 parts by weight of the resin binder.

The charge control agent is not particularly limited. The negativelychargeable charge control agent includes metal-containing azo dyes, forexample, “BONTRON S-28” (commercially available from Orient ChemicalCo., Ltd.), “T-77” (commercially available from Hodogaya Chemical Co.,Ltd.), “BONTRON S-34” (commercially available from Orient Chemical Co.,Ltd.), “AIZEN SPILON BLACK TRH” (commercially available from HodogayaChemical Co., Ltd.), and the like; copper phthalocyanine dyes; metalcomplexes of alkyl derivatives of salicylic acid, for example, “BONTRONE-81,” “BONTRON E-84,” “BONTRON E-304” (hereinabove commerciallyavailable from Orient Chemical Co., Ltd.), and the like; nitroimidazolederivatives; boron complexes of benzilic acid, for example, “LR-147”(commercially available from Japan Carlit, Ltd.); nonmetallic chargecontrol agents, for example, “BONTRON F-21,” “BONTRON E-89” (hereinabovecommercially available from Orient Chemical Co., Ltd.), “T-8”(commercially available from Hodogaya Chemical Co., Ltd.), “FCA-2521NJ,”“FCA-2508N” (hereinabove commercially available from FUJIKURA KASEI CO.,LTD.), and the like.

The positively chargeable charge control agent includes Nigrosine dyes,for example, “BONTRON N-01,” “BONTRON N-04,” “BONTRON N-07” (hereinabovecommercially available from Orient Chemical Co., Ltd.), “CHUO CCA-3”(commercially available from CHUO GOUSEI KAGAKU CO., LTD.), and thelike; triphenylmethane-based dyes containing a tertiary amine as a sidechain; quaternary ammonium salt compounds, for example, “BONTRON P-51”(commercially available from Orient Chemical Co., Ltd.), “TP-415”(commercially available from Hodogaya Chemical Co., Ltd.),cetyltrimethylammonium bromide, “COPY CHARGE PX VP435” (commerciallyavailable from Clariant Japan, Ltd.), and the like.

The charge control agent is contained in an amount of preferably 0.1parts by weight or more, and more preferably 0.2 parts by weight ormore, based on 100 parts by weight of the resin binder, from theviewpoint of adjustment of triboelectric charges of the toner to anappropriate level to improve developability, and from the viewpoint ofsuppression in fall-off of a toner. In addition, the charge controlagent is contained in an amount of preferably 5 parts by weight or less,and more preferably 3 parts by weight or less, based on 100 parts byweight of the resin binder, from the viewpoint of suppression inbackground fogging of the toner. In other words, taken together theseviewpoints, the charge control agent is contained in an amount ofpreferably from 0.1 to 5 parts by weight, and more preferably from 0.2to 3 parts by weight, based on 100 parts by weight of the resin binder.

The toner in the present invention may further properly contain anadditive such as a magnetic particulate, a fluidity improver, anelectric conductivity modifier, an extender pigment, a reinforcingfiller such as a fibrous material, an antioxidant, an anti-aging agent,or a cleanability improver.

The toner in the present invention is obtained by a method including thesteps of:

melt-kneading at least a resin binder containing a crystalline resin andan amorphous resin and a colorant (step 1); and

heat-treating the kneaded product obtained in the step 1 (step 2).

The step 1 of melt-kneading raw materials for a toner containing atleast a crystalline resin and an amorphous resin and a colorant, inother words, a crystalline resin, an amorphous resin, a colorant and thelike can be carried out with a known kneader, such as a closed kneader,a single-screw or twin-screw extruder, or a continuous open-roller typekneader. Since the additives can be efficiently highly dispersed in theresin binder without repeats of kneading or without a dispersion aid, acontinuous open-roller type kneader provided with feeding ports and adischarging port for a kneaded product along the shaft direction of theroller is preferably used.

It is preferable that the raw materials for a toner are previouslyhomogeneously mixed with a Henschel mixer, a Super-Mixer or the like,and thereafter fed to an open-roller type kneader, and the raw materialsmay be fed from one feeding port, or dividedly fed to the kneader fromplural feeding ports. It is preferable that the raw materials for thetoner are fed to the kneader from one feeding port, from the viewpointof easiness of operation and simplification of an apparatus.

The continuous open-roller type kneader refers to a kneader of whichkneading member is an open type, not being tightly closed, and thekneading heat generated during the kneading can be easily dissipated. Inaddition, it is desired that the continuous open-roller type kneader isa kneader provided with at least two rollers. The continuous open-rollertype kneader preferably used in the present invention is a kneaderprovided with two rollers having different peripheral speeds, in otherwords, two rollers of a high-rotation roller having a high peripheralspeed and a low-rotation roller having a low peripheral speed. In thepresent invention, it is desired that the high-rotation roller is a heatroller, and the low-rotation roller is a cooling roller, from theviewpoint of dispersibility.

The temperature of the roller can be adjusted by, for example, atemperature of a heating medium passing through the inner portion of theroller, and each roller may be divided in two or more portions in theinner portion of the roller, each being communicated with heating mediaof different temperatures.

The temperature at the end part of the raw material supplying side ofthe high-rotation roller is preferably from 100° to 160° C., and thetemperature at the end part of the raw material supplying side of thelow-rotation roller is preferably from 35° to 100° C.

In the high-rotation roller, the difference between a settingtemperature at the end part of the raw material supplying side and asetting temperature at the end part of the kneaded product dischargingside is preferably from 20° to 60° C., more preferably from 20° to 50°C., and even more preferably from 30° to 50° C., from the viewpoint ofpreventing detachment of the kneaded product from the roller. In thelow-rotation roller, the difference between a setting temperature at theend part of the raw material supplying side and a setting temperature atthe end part of the kneaded product discharging side is preferably from0° to 50° C., more preferably from 0° to 40° C., and even morepreferably from 0° to 20° C., from the viewpoint of dispersibility ofthe releasing agent.

The peripheral speed of the high-rotation roller is preferably from 2 to100 m/min, and more preferably from 4 to 50 m/min. The peripheral speedof the low-rotation roller is preferably from 1 to 90 m/min, morepreferably from 2 to 60 m/min, and even more preferably from 2 to 50m/min. In addition, the ratio between the peripheral speeds of the tworollers, i.e., low-rotation roller/high-rotation roller, is preferablyfrom 1/10 to 9/10, and more preferably from 3/10 to 8/10.

Structures, size, materials and the like of the roller are notparticularly limited. Also, the surface of the roller may be any ofsmooth, wavy, rugged, or other surfaces. In order to increase kneadingshare, it is preferable that plural spiral ditches are engraved on thesurface of each roller.

The step 2 is a step of heat-treating the kneaded product obtained inthe step 1. The heat-treating step may be carried out in any steps,subsequent to the kneading step. Although the method of the presentinvention can be applied to the production of a pulverized tonerprepared by pulverizing a kneaded product to provide a toner, or to theproduction of a polymerization toner obtained by dispersing a kneadedproduct as particles in a solvent, it is preferable that the method isused in the production of a pulverized toner that does not include astep of carrying thermal treatment other than the heat-treating step. Inthe present invention, in the production of a pulverized toner, akneaded product obtained by the melt-kneading step is pulverized, andthe resulting pulverized product may then be subjected to aheat-treating step, so long as a phase separation structure of acrystalline resin and an amorphous resin in the kneaded product isstabilized by the thermal treatment so that re-crystallization of thecrystalline polyester is accelerated. It is preferable that theheat-treating step is carried out subsequent to the kneading step butprior to the pulverizing step, from the viewpoint of suppression infilming of the toner on a photoconductor or fall-off of the toner.

In a general method for producing a toner for a pulverized toner, theresulting kneaded product is cooled to a point of attaining apulverizable hardness, and then subjected to a pulverizing step and aclassifying step; however, in the present invention, it is preferablethat a pulverizing step is carried out subsequent to the kneading step,and after subjecting the resulting kneaded product to a heat-treatingstep, as mentioned above.

In the present invention, the temperature for the heat-treating step ispreferably equal or higher than a glass transition temperature of thekneaded product, more preferably a temperature calculated from a glasstransition temperature plus 10° C. or more, and even more preferably atemperature calculated from a glass transition temperature plus 15° C.or more, from the viewpoint of maintaining dispersibility of toneradditives, from the viewpoint of rearrangement of resin bindermolecules, thereby providing suppression in filming of a toner on aphotoconductor and fall-off of a toner during the durability printing,and from the viewpoint of shortening the heat-treatment time, therebyimproving productivity of the toner. In addition, the temperature forthe heat-treating step is preferably a temperature equal to or lowerthan a melting point of the crystalline resin, more preferably atemperature calculated from a melting point minus 10° C. or more, andeven more preferably a temperature calculated from a melting point minus15° C. or more, from the viewpoint of preventing filming of a toner on aphotoconductor due to disorder of arrangements accompanying dissolutionof the crystals. Specifically, it is desired that the heat-treatmentstep is carried out at a temperature of from 50° to 80° C., and morepreferably from 60° to 80° C.

In addition, the heat treatment time is preferably 2 hours or longer,more preferably 3 hours or longer, and even more preferably 5 hours orlonger, from the viewpoint of suppression in filming of a toner on aphotoconductor and fall-off of a toner during durability printing. Also,the heat treatment time is preferably 25 hours or shorter, morepreferably 12 hours or shorter, and even more preferably 8 hours orshorter, from the viewpoint of increasing productivity of the toner. Inother words, taken together these viewpoints, the heat treatment time ispreferably from 2 to 25 hours, more preferably from 3 to 12 hours, andeven more preferably from 5 to 8 hours. Here, this heat treatment timeis a cumulative time at which the temperature is within the temperaturerange defined above (a temperature equal to or higher than the glasstransition temperature of the kneaded product and equal to lower thanthe melting point of the crystalline resin). In addition, it ispreferable that the temperature does not exceed the upper limit of thetemperature range defined above from the beginning to the end of theheat-treating step, from the viewpoint of maintaining dispersibility ofthe toner additives.

In the present invention, the heat-treating step is carried out at thetemperature defined above for the time as defined above, whereby it isdeduced that the rearrangement of the resin in the kneaded product isaccelerated, so that the glass transition temperature of the kneadedproduct once lowered is again elevated, thereby providing suppression infilming of a toner on a photoconductor, a more remarkable improvement intriboelectric stability, and suppression in fall-off of a toner.Further, a plastic part, in other words a part having a low-glasstransition temperature, is likely to absorb shock during thepulverization, thereby giving causations for lowering a pulverizationefficiency. In the present invention, since the plasticization issuppressed by carrying out the heat-treating step before the pulverizingstep, the pulverizability can be also improved.

In the heat-treating step, an oven or the like can be used. For example,in a case where an oven is used, a heat-treating step can be carried outby maintaining a kneaded product in the oven at a given temperature.

Embodiments for carrying out the heat-treating step are not particularlylimited, and include, for example:

Embodiment 1

an embodiment including the steps of, subsequent to a kneading step,pulverizing a kneaded product in a pulverizing step, and keeping apulverized kneaded product under the heat-treatment conditions mentionedabove;

Embodiment 2

an embodiment including the steps of, subsequent to a kneading step,keeping a kneaded product under the heat-treatment conditions mentionedabove in the process of cooling the resulting kneaded product, furthercooling the kneaded product to a point of attaining a pulverizablehardness, and subjecting the cooled product to a subsequent step such asa pulverizing step;

Embodiment 3

an embodiment including the steps of, subsequent to a kneading step,once cooling the resulting kneaded product to a pulverizable hardness,subjecting the cooled kneaded product to the above-mentionedheat-treating step, cooling the kneaded product again, and subjectingthe cooled product to a subsequent step such as a pulverizing step;

and the like. In the present invention, the heat-treating step may becarried out in any of the Embodiments, and Embodiment 3 is preferredfrom the viewpoint of dispersibility of additives in a toner.

In the present invention, in the pulverizing step, pulverization may becarried out while mixing a production intermediate with fine inorganicparticles. For example, pulverization may be carried out while mixingsilica and a production intermediate.

The pulverizing step may be carried out in divided multi-stages. Forexample, the heat-treated product after the heat-treating step may beroughly pulverized to a size of from 1 to 5 mm or so, and the roughlypulverized product may be further finely pulverized to a desiredparticle size.

The pulverizer used in the pulverization step is not particularlylimited. For example, the pulverizer used preferably in the roughpulverization includes an atomizer, Rotoplex, and the like, and thepulverizer used preferably in the fine pulverization includes a jetmill, an impact type mill, a rotary mechanical mill, and the like.

The classifier used in the classifying step includes an air classifier,a rotor type classifier, a sieve classifier, and the like. Thepulverized product which is insufficiently pulverized and removed duringthe classifying step may be subjected to the pulverization step again.

The toner obtained by the present invention has a volume-median particlesize (D₅₀) of preferably from 3.0 to 12 μm, more preferably from 3.5 to10 μm, and even more preferably from 4 to 9 μm, from the viewpoint ofimproving the image quality. The term “volume-median particle size(D₅₀)” as used herein means a particle size of which cumulative volumefrequency calculated on a volume percentage is 50% counted from thesmaller particle sizes.

The toner in the present invention may be obtained by a method includingthe step of further mixing a toner after a pulverizing step and aclassifying step, with an external additive such as fine inorganicparticles made of silica or the like, or fine resin particles made ofpolytetrafluoroethylene or the like.

In the mixing of a pulverized product or the toner particles obtainedafter a classifying step with an external additive, an agitator havingan agitating member such as rotary impellers is preferably used, and amore preferred agitator includes a Henschel mixer.

The toner in the present invention can be either directly used as atoner for monocomponent development, or used as a two-componentdeveloper containing a toner mixed with a carrier in an apparatus forforming fixed images of a monocomponent development or a two-componentdevelopment.

The toner in the present invention can be suitably used in an apparatusfor forming fixed images according to a nonmagnetic monocomponentdevelopment method which is exposed to an even greater mechanical orthermal stress, from the viewpoint of suppression in filming of a toneron a photoconductor and fall-off of a toner. Further, the toner in thepresent invention can also be suitably used in an apparatus for formingfixed images according to an oil-less nonmagnetic monocomponentdevelopment method, from the same viewpoint. Here, the oil-less fusingrefers to a method in which a fixing apparatus having a heat rollerfixing apparatus without being equipped with an oil feeding device isused. The oil feeding device encompasses a device having an oil tank,and a mechanism in which an oil is applied in a given amount to a heatroller surface, and a device having a mechanism in such a manner that aroller previously immersed in an oil is contacted with a heat roller,and the like.

EXAMPLES

The following examples further describe and demonstrate embodiments ofthe present invention. The examples are given solely for the purposes ofillustration and are not to be construed as limitations of the presentinvention.

[Softening Point of Resin]

The softening point refers to a temperature at which half of the sampleflows out, when plotting a downward movement of a plunger of a flowtester (commercially available from Shimadzu Corporation, CAPILLARYRHEOMETER “CFT-500D”), against temperature, in which a 1 g sample isextruded through a nozzle having a die pore size of 1 mm and a length of1 mm with applying a load of 1.96 MPa thereto with the plunger, whileheating the sample so as to raise the temperature at a rate of 6°C./min.

[Temperature of Maximum Endothermic Peak and Melting Point of Resin]

Measurements were taken using a differential scanning calorimeter(“Q-100,” commercially available from TA Instruments, Japan), by coolinga 0.01 to 0.02 g sample weighed out in an aluminum pan from roomtemperature to 0° C. at a cooling rate of 10° C./min, allowing thecooled sample to stand for 1 minute, and thereafter heating the sampleat a rate of 50° C./min. Among the endothermic peaks observed, thetemperature of an endothermic peak on the highest temperature side isdefined as a temperature of maximum endothermic peak. When a differencebetween the temperature of maximum endothermic peak and the softeningpoint is within 20° C., the temperature of maximum endothermic peak isdefined as a melting point.

[Glass Transition Temperatures (Tg) of Amorphous Resin and KneadedProduct]

Measurements were taken using a differential scanning calorimeter(“Q-100,” commercially available from TA Instruments, Japan), by heatinga 0.01 to 0.02 g sample weighed out in an aluminum pan to 200° C.,cooling the sample from that temperature to 0° C. at a cooling rate of10° C./min, and raising the temperature of the sample at a rate of 10°C./min. A temperature of an intersection of the extension of thebaseline of equal to or lower than the temperature of maximumendothermic peak and the tangential line showing the maximum inclinationbetween the kick-off of the peak and the top of the peak in the abovemeasurement is defined as a glass transition temperature.

[Glass Transition Temperatures (Tg) of Crystalline Resin (CompositeResin)]

Measurements were taken using a differential scanning calorimeter(“Q-100,” commercially available from TA Instruments, Japan) in amodulated mode, by heating a 0.01 to 0.02 g sample weighed out in analuminum pan to 200° C., cooling the sample from that temperature to−80° C. at a cooling rate of 100° C./min, and raising the temperature ofthe sample at a rate of 1° C./min. A temperature of an intersection ofthe extension of the baseline of equal to or lower than the temperatureof maximum endothermic peak and the tangential line showing the maximuminclination between the kick-off of the peak and the top of the peak inthe above measurement is defined as a glass transition temperature.

[Acid Value of Resin]

The acid value is determined by a method according to JIS K0070 exceptthat only the determination solvent is changed from a mixed solvent ofethanol and ether as defined in JIS K0070 to a mixed solvent of acetoneand toluene (volume ratio of acetone: toluene=1:1).

[Melting Point of Releasing Agent]

A temperature of maximum endothermic peak of the heat of fusion obtainedby raising the temperature of a sample to 200° C., cooling the samplefrom this temperature to 0° C. at a cooling rate of 10° C./min, andthereafter raising the temperature of the sample at a heating rate of10° C./min, using a differential scanning calorimeter (“DSC 210,”commercially available from Seiko Instruments, Inc.) is referred to as amelting point.

[Volume-Median Particle Size (D₅₀) of Toner]

Measuring Apparatus Coulter Multisizer II (commercially available fromBeckman Coulter, Inc.)

Aperture Diameter: 50 μm

Analyzing Software: Coulter Multisizer AccuComp Ver. 1.19 (commerciallyavailable from Beckman Coulter, Inc.)Electrolytic solution: “Isotone II” (commercially available from BeckmanCoulter, Inc.)Dispersion: “EMULGEN 109P” (commercially available from Kao Corporation,polyoxyethylene lauryl ether, HLB: 13.6) is dissolved in the aboveelectrolytic solution so as to have a concentration of 5% by weight toprovide a dispersion.Dispersion Conditions Ten milligrams of a measurement sample is added to5 ml of the above dispersion, and the mixture is dispersed for 1 minutewith an ultrasonic disperser, and 25 ml of the above electrolyticsolution is added to the dispersion, and further dispersed with anultrasonic disperser for 1 minute, to prepare a sample dispersion.Measurement Conditions The above sample dispersion is added to 100 ml ofthe above electrolytic solution to adjust to a concentration at whichparticle sizes of 30,000 particles can be measured in 20 seconds, andthereafter the 30,000 particles are measured, and a volume-medianparticle size (D₅₀) is obtained from the particle size distribution.

[Production Examples of Crystalline Resins (Composite Resins) A to E]

A 10-liter four-neck flask equipped with a nitrogen inlet tube, adehydration tube, a stirrer, and a thermocouple was charged with rawmaterial monomers for a polycondensation resin component other than adually reactive monomer acrylic acid in given amounts listed in Table 1,and the contents were heated to 160° C. to dissolve. A solution preparedby previously mixing styrene, dicumyl peroxide, and acrylic acid wasadded dropwise thereto from a dropping funnel over a period of 1 hour.The mixture was continued stirring for 1 hour while keeping thetemperature at 170° C. to allow polymerization between styrene andacrylic acid. Subsequently, 40 g of tin(II) 2-ethylhexanoate and 3 g ofgallic acid were added thereto, the temperature of the contents wasraised to 210° C., and the components were reacted for 8 hours. Further,the components were reacted at 8.3 kPa for 1 hour, to provide each ofCrystalline Resins A to E. The physical properties of the resultingCrystalline Resins are shown in Table 1.

TABLE 1 Crystalline Resin A B C D E Raw Material Monomers Raw MaterialMonomers for Polycondensation Resin Component (P)¹⁾ 1,6-Hexanediol 100(3540 g) 100 (4130 g) 100 (2950 g) 100 (4248 g) 100 (2360 g)Terephthalic Acid  78 (3884 g)  88 (5113 g)  60 (2490 g)  90 (5378 g) 48 (1594 g) Acrylic Acid (Dually Reactive Monomer)  7 (151 g) 2 (50 g)15 (270 g) 1 (26 g) 20 (288 g) Raw Material Monomers for Styrenic ResinComponent (S)²⁾ Styrene 100 (1782 g) 100 (492 g)  100 (3486 g) 100 (163g)  100 (5643 g) Dicumyl Peroxide (Polymerization Initiator)  6 (107 g)6 (30 g)  6 (209 g) 6 (10 g)  6 (339 g) Total Amount of P/Total Amountof S (Weight Ratio)³⁾ 81/19 95/5 62/38 98/2 43/57 Number of Moles ofDually Reactive Monomer per 100 mol of 12 15 11 23 7 Total Number ofMoles of S⁴⁾ Physical Properties of Crystalline Resins Glass TransitionTemp (° C.) of Styrenic Resin 100 100 100 100 100 Component According toFox Formula (Tg1) Glass Transition Temperature (° C.) of CrystallineResin (Tg2) 16 4 25 2 46 Tg1 − Tg2 84 96 75 98 54 Softening Point (° C.)130 138 105 140 92 Temperature of Maximum Endothermic Peak 129 135 112137 96 [Melting Point] (° C.) Ratio of Softening Point/Temperature of1.01 1.02 0.94 1.02 0.96 Maximum Endothermic Peak ¹⁾Numerical valuesshow amounts (number of mol supposing that a total amount of the alcoholcomponent is 100), and the numerical values inside parentheses showweight. ²⁾Numerical values show amounts (weight ratio supposing that rawmaterial monomers for the styrenic component is 100), and the numericalvalues inside parentheses show weight. ³⁾A total amount of the rawmaterial monomers for the styrenic resin component does not includedicumyl peroxide. ⁴⁾A total number of moles of the raw material monomersfor the styrenic resin component does not include dicumyl peroxide.

[Production Example of Crystalline Resin F]

A 5-liter four-neck flask equipped with a nitrogen inlet tube, adehydration tube, a stirrer, and a thermocouple was charged with 870 gof 1,6-hexanediol, 1575 g of 1,4-butanediol, 2950 g of fumaric acid, 2 gof hydroquinone, 40 g of tin(II) 2-ethylhexanoate, and 3 g of gallicacid, the component were reacted at 160° C. in a nitrogen atmosphereover a period of 5 hours, the temperature was raised to 200° C., and thecomponents were reacted for an additional 1 hour. Further, thecomponents were reacted at 8.3 kPa until the softening point reached110° C., to provide Crystalline Resin F. Crystalline Resin F obtainedhad a softening point of 112° C., a temperature of maximum endothermicpeak of 110° C., and a ratio of [softening point/temperature of maximumendothermic peak] of 1.02.

[Production Example of Crystalline Resin G]

A 5-liter four-neck flask equipped with a nitrogen inlet tube, adehydration tube, a stirrer, and a thermocouple was charged with 1416 gof 1,6-hexanediol, 1693 g of terephthalic acid, 259 g of adipic acid, 6g of dibutyltin oxide, and 3 g of gallic acid, and the components werereacted at 200° C. in a nitrogen atmosphere for 6 hours. Further, thecomponents were reacted at 8.3 kPa for 3 hours, to provide CrystallineResin G. Crystalline Resin G obtained had a softening point of 113° C.,a temperature of maximum endothermic peak of 124° C., and a ratio of[softening point/temperature of maximum endothermic peak] of 0.91.

[Production Example 1 of Amorphous Polyester]

A 5-liter four-neck flask equipped with a nitrogen inlet tube, adehydration tube, a stirrer, and a thermocouple was charged with 1286 gof polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane, 2218 g ofpolyoxyethylene(2.2)-2,2-bis(4-hydroxyphenyl)propane, 1603 g ofterephthalic acid, 10 g of tin(II) 2-ethylhexanoate, and 2 g of gallicacid, and the components were reacted at 230° C. in a nitrogenatmosphere until the reaction percentage reached 90%, and then reactedat 8.3 kPa until the softening point reached 111° C., to provide anamorphous polyester (Resin a). The resin a had a glass transitiontemperature of 69° C., a softening point of 111° C., a temperature ofmaximum endothermic peak of 71° C., a ratio of [softeningpoint/temperature of maximum endothermic peak] of 1.6, and an acid valueof 3.2 mg KOH/g. Here, the reaction percentage refers to a valuecalculated by [amount of water generated/theoretical amount of watergenerated]×100.

[Production Example 2 of Amorphous Polyester]

A 10-liter four-neck flask equipped with a nitrogen inlet tube, adehydration tube, a stirrer, and a thermocouple was charged with 3486 gof polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane, 3240 g ofpolyoxyethylene(2.2)-2,2-bis(4-hydroxyphenyl)propane, 1881 g ofterephthalic acid, 269 g of tetrapropenylsuccinic acid anhydride, 30 gof tin(II) 2-ethylhexanoate, and 2 g of gallic acid, and the componentswere reacted at 230° C. in a nitrogen atmosphere until the reactionpercentage reached 90%, and then reacted at 8.3 kPa for 1 hour. Next,789 g of trimellitic anhydride was supplied to the reaction mixture, andthe components were reacted at 220° C. until a softening point reached122° C., to provide an amorphous polyester (Resin b). The resin b had aglass transition temperature of 64° C., a softening point of 122° C., atemperature of maximum endothermic peak of 65° C., a ratio of [softeningpoint/temperature of maximum endothermic peak] of 1.9, and an acid valueof 18.9 mg KOH/g.

[Examples 1 to 10 and Comparative Examples 1 to 10]

Resin a, Resin b, and a crystalline resin in amounts listed in Table 2,0.2 parts by weight of a negatively chargeable charge control agent“E-304” (commercially available from Orient Chemical Co., Ltd.), 3 partsby weight of Carnauba Wax C1(commercially available from S. Kato & CO.,melting point: 88° C.), 3 parts by weight of a paraffinic wax “HNP-9”(commercially available from NIPPON SEIRO CO., LTD., melting point: 75°C.), and 5.0 parts by weight of a colorant “ECB-301” (commerciallyavailable from DAINICHISEIKA COLOR & CHEMICALS MFG. CO., LTD.,phthalocyanine blue (P.B. 15:3)) were mixed with a Henschel mixer for 1minute, and the mixture was then melt-kneaded under the followingconditions.

A continuous twin open-roller type kneader “Kneadex” (commerciallyavailable from MITSUI MINING COMPANY, LIMITED, outer diameter of roller:14 cm, effective length of roller: 80 cm) was used. The operatingconditions are a peripheral speed of a high-rotation roller (frontroller) of 75 r/min (32.97 m/min), a peripheral speed of a low-rotationroller (back roller) of 50 r/min (21.98 m/min), and a gap between therollers at the end part of the feeding ports of the kneaded mixture of0.1 mm. The temperatures of the heating medium and the cooling mediuminside the rollers are as follows. The high-rotation roller had atemperature at the raw material supplying side of 135° C., and atemperature at the kneaded mixture discharging side of 90° C., and thelow-rotation roller has a temperature at the raw material supplying sideof 35° C., and a temperature at the kneaded mixture discharging side of35° C. In addition, the feeding rate of the raw material mixture was 4kg/hour, and the average residence time was about 10 minutes.

The kneaded mixture obtained above was pressed with a cooling roller tocool it to 20° C. or lower, and the pressed product was heat-treated inan oven at a temperature listed in Table 2 for a time period listed inTable 2.

The heat-treated product after the heat treatment was cooled to 30° C.,and the cooled product was roughly pulverized to a size of 3 mm withRotoplex (commercially available from TOA KIKAI SEISAKUSHO). Thereafter,the roughly pulverized product was pulverized with a fluidized bed-typejet mill “AFG-400” (commercially available from HOSOKAWA ALPINE A.G.),the pulverized product was classified with a rotor-type classifier“TTSP” (commercially available from HOSOKAWA ALPINE A.G.), to providetoner matrix particles having a volume-median particle size (D₅₀) of 8.0μm. To 100 parts by weight of the toner matrix particles were added 1.0part by weight of a hydrophobic silica “RY50” (commercially availablefrom Nippon Aerosil Co., Ltd.), and 0.5 parts by weight of a hydrophobicsilica “R972” (commercially available from Nippon Aerosil Co., Ltd.)with a Henschel mixer (commercially available from MITSUI MININGCOMPANY, LIMITED) at 1500 r/min for one minute, to provide a toner.

Test Example 1 [Low-Temperature Fixing Ability]

Each toner was loaded in a nonmagnetic monocomponent developer device“OKI MICROLINE 5400” (commercially available from Oki Data Corporation).With adjusting the amount of toner adhesion to 0.60 mg/cm², a solidimage of 30 mm×80 mm was printed on Xerox L sheet (A4). The solid imagewas taken out before passing through a fixing device, to provide anunfixed image. The resulting unfixed image was fixed with an externalfixing device, a modified fixing device of “OKI MICROLINE 3010”(commercially available from Oki Data Corporation), while setting thetemperature of the fixing roller to 100° C. and a fixing speed to 100mm/sec. Thereafter, the same procedures were carried out with settingthe fixing roller temperature at 105° C., and raising the temperature to200° C. in an increment of 5° C.

A plain white sheet (Xerox L sheet) was wound around a 500 g weight ofwhich bottom had an area of 20 mm×20 mm, and placed over a portion ofthe solid image fixed at each temperature and reciprocated 20 time in awidth of 14 cm. Thereafter, each of image densities of the rubbedportion and the non-rubbed portion of the solid image was measured witha reflective densitometer “RD-915” (commercially available from MacbethProcess Measurements Co.), and a percentage of lowered image densities:

[Image density of rubbed portion/Image density of non-rubbedportion]×100

was obtained. An initial temperature at which the percentage of thelowered image density was 70% or more is defined as a lowest fixingtemperature. The results are shown in Table 2. Those toners having alowest fixing temperature of 140° C. or lower were evaluated asexcellent.

Test Example 2 [Durability]

Each toner was loaded in a nonmagnetic monocomponent developer device“OKI MICROLINE 5400” (commercially available from Oki Data Corporation),and a durability test was conducted at a printed coverage of 5% underenvironmental conditions of 25° C. and 50% RH (relative humidity). Solidimages were printed out on full page every 1000 sheet printouts, andwhite spots caused by filming of the toner on a photoconductor werevisually observed. The test was halted at a point where the generationof white spots was confirmed, and the test was conducted on 12,000sheets at most. Those with 10000 sheets or more printouts wereconsidered acceptable.

Test Example 3 [Fall-Off of Toner]

A photoconductor was removed from a cartridge for a nonmagneticmonocomponent developer device “OKI MICROLINE 5400” (commerciallyavailable from Oki Data Corporation), and 30 g of a toner was loaded inthe cartridge. The developer roller was rotated for 1 hour at a rate of70 r/min (equivalent to 36 ppm). The weight of the toner fallen off fromthe developer roller was measured, and evaluated as fall-off of toner.Those toners having fall-off of toner of 500 mg or less were evaluatedas excellent.

TABLE 2 Amorphous Resins Crystalline Weight Ratio¹⁾ of Low-TemperatureResin a, Resin b, Resin Polycondensation Resin Tg (° C.) of Heat- FixingAbility Fall-off Parts by Parts by Parts by Component/ Kneaded Treatment(Lowest Fixing Durability of Toner Weight Weight Kinds Weight StyrenicResin Component Product Conditions Temp. (° C.)) (sheets) (mg) Ex. 1 6030 A 10 81/19 51 65° C. for 24 hr 130 >12000 180 Ex. 2 60 30 A 10 81/1951 70° C. for 24 hr 130 >12000 100 Ex. 3 60 30 A 10 81/19 51 70° C. for12 hr 130 >12000 150 Ex. 4 60 30 A 10 81/19 51 70° C. for 3 hr 125 11000200 Ex. 5 60 30 A 10 81/19 51 75° C. for 12 hr 130 >12000 120 Ex. 6 6030 B 10 95/5  48 70° C. for 24 hr 135 >12000 200 Ex. 7 60 30 C 10 62/3853 70° C. for 24 hr 135 11000 330 Ex. 8 60 35 A 5 81/19 55 70° C. for 24hr 140 >12000 350 Ex. 9 60 20 A 20 81/19 47 70° C. for 24 hr 120 >12000400 Ex. 10 60 10 A 30 81/19 42 70° C. for 24 hr 120 >12000 480 Comp. 6030 A 10 81/19 51 — 125 7000 1120 Ex. 1 Comp. 60 38 A 2 81/19 57 70° C.for 24 hr 150 >12000 780 Ex. 2 Comp. — 50 A 50 81/19 40 70° C. for 24 hr120 9000 980 Ex. 3 Comp. 60 30 D 10 98/2  52 70° C. for 24 hr 145 11000680 Ex. 4 Comp. 60 30 E 10 43/57 54 70° C. for 24 hr 145 >12000 720 Ex.5 Comp. 60 30 F 10 100/0  50 70° C. for 24 hr 130 11000 1150 Ex. 6 Comp.60 30 F 10 100/0  50 70° C. for 3 hr 130 7000 1250 Ex. 7 Comp. 60 30 G10 100/0  46 70° C. for 24 hr 130 10000 1420 Ex. 8 Comp. 60 30 G 10100/0  46 70° C. for 3 hr 130 7000 1490 Ex. 9 Comp. 70 30 — — — 64 70°C. for 24 hr 150 >12000 510 Ex. 10 ¹⁾Total weight of raw materialmonomers for the polycondensation resin component/Total weight of rawmaterial monomers for styrenic resin component

It can be seen from the above results that the toners of Examples 1 to10 have excellent low-temperature fixing ability and suppressed filmingon a photoconductor and fall-off of the toner.

On the other hand, the toner of Comparative Example 1 where no heattreatment was conducted and the toner of Comparative Example 3 where thecomposite resin (=crystalline resin) is contained in a large amount donot show suppression in filming on a photoconductor or fall-off of thetoner. In addition, the toner of Comparative Example 2 where thecomposite resin of the present invention (=crystalline resin) iscontained in a smaller amount has poor low-temperature fixing abilityand has larger fall-off of the toner. The toners of Comparative Examples4 and 5 where the weight ratio of the polycondensation resincomponent/styrenic resin component is outside a given range, or thetoners of Comparative Examples 6 to 9 where a crystalline resindifferent from the crystalline resin in the present invention is usedhave larger fall-off of toner. Further, the toners of ComparativeExamples 7 and 9 where the heat treatment time is shorter showgeneration of filming on a photoconductor. The toner of ComparativeExample 10 without using a crystalline resin has poor low-temperaturefixing ability and larger fall-off of toner.

In addition, it can be seen from the comparison between the toner ofExample 4 and the toners of Comparative Examples 7 and 9 that the tonerobtained by the method of the present invention has suppression infilming on a photoconductor and fall-off of toner even when the heattreatment time is shorter, thereby having excellent productivity in themethod of the toner of the Examples.

The toner obtained by the method of the present invention is used in,for example, the development of a latent image formed inelectrophotography, electrostatic recording method, electrostaticprinting method or the like.

The present invention being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. A method for producing a toner comprising the steps of: melt-kneadingat least a resin binder and a colorant to give a kneaded product (step1); and heat-treating the kneaded product obtained in the step 1 (step2), wherein the resin binder comprises a crystalline resin and anamorphous resin, wherein the crystalline resin comprises a compositeresin comprising: (a) a polycondensation resin component obtained bypolycondensing an alcohol component comprising an aliphatic diol having2 to 10 carbon atoms and a carboxylic acid component comprising anaromatic dicarboxylic acid compound, and (b) a styrenic resin component,wherein a weight ratio of the polycondensation resin component to thestyrenic resin component in the composite resin, i.e. polycondensationresin component/styrenic resin component, is from 50/50 to 95/5, andwherein the composite resin is contained in an amount of from 5 to 40%by weight of the resin binder.
 2. The method according to claim 1,wherein the composite resin is a resin obtained by polymerizing: (i) rawmaterial monomers for the polycondensation resin component, comprisingan alcohol component comprising an aliphatic diol having 2 to 10 carbonatoms and a carboxylic acid component comprising an aromaticdicarboxylic acid compound; (ii) raw material monomers for the styrenicresin component; and (iii) a dually reactive monomer capable of reactingwith both of the raw material monomers for the polycondensation resincomponent and the raw material monomers for the styrenic resincomponent.
 3. The method according to claim 2, wherein the duallyreactive monomer is used in an amount of from 2 to 30 mol based on 100mol of a total of the raw material monomers for the styrenic resincomponent.
 4. The method according to claim 1, wherein an absolute valueof a difference between a glass transition temperature of the compositeresin and a glass transition temperatures of the styrenic resincomponent in the composite resin as calculated by Fox formula is 10° C.or more.
 5. The method according to claim 1, wherein the step 2comprises keeping the kneaded product at a temperature between equal toor higher than a glass transition temperature of the kneaded product andequal to or lower than a melting point of the crystalline resin for 2 to25 hours.
 6. The method according to claim 1, wherein a weight ratio ofthe crystalline resin to the amorphous resin, i.e. crystallineresin/amorphous resin, is from 5/95 to 40/60.